[mips] Disable tail merging when long branch pass is enabled.
llvm-svn: 192124
diff --git a/llvm/lib/Target/Mips/MipsTargetMachine.cpp b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
index 06f78e0..5046c1b 100644
--- a/llvm/lib/Target/Mips/MipsTargetMachine.cpp
+++ b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
@@ -135,7 +135,13 @@
class MipsPassConfig : public TargetPassConfig {
public:
MipsPassConfig(MipsTargetMachine *TM, PassManagerBase &PM)
- : TargetPassConfig(TM, PM) {}
+ : TargetPassConfig(TM, PM) {
+ // The current implementation of long branch pass requires a scratch
+ // register ($at) to be available before branch instructions. Tail merging
+ // can break this requirement, so disable it when long branch pass is
+ // enabled.
+ EnableTailMerge = !getMipsSubtarget().enableLongBranchPass();
+ }
MipsTargetMachine &getMipsTargetMachine() const {
return getTM<MipsTargetMachine>();